Abyssal flow is a common geological phenomenon, and abyssal transport sedimentation caused by abyssal flow is a relatively common sedimentary form. The abyssal flow sediments are often dominated by fine shoulder sediments, volcanic materials, or siliceous sediments, and also characterized by a common horizontal micro-layering. The abyssal flow transport sedimentation has a significant impact on the seabed and topographic reconstruction. Combined with the abyssal flow sedimentary motion state obtained by geological drilling, it is of great guiding significance to the study of the evolution of abyssal geological structures. By observing the dynamic change of the super-pore pressure value in the superficial sediments of the seabed, it is possible to obtain the abyssal flow transport sedimentation state relatively intuitively.
The conventional means of obtaining the super-pore pressure value in the superficial sediments of the seabed is to embed a pore pressure sensor by way of pore drilling for long-term observation. The specific implementation method is that the underwater robot is used to embed the pore pressure sensor at a certain position in the soil layer, and grouting and sealing are performed to prevent the sensor from contacting the external water environment, resulting in inaccurate measurement. The obtained pore water pressure value is corrected and converted into a super-pore pressure value, and further analysis is performed to obtain the influence of the abyssal flow transport sedimentation on the state of the sedimentary layer.
With the development of the technology, most of the existing pressure sensors can achieve differential pressure measurement. Among them, the optical fiber grating sensor has the characteristics of corrosion prevention and being water proof, which provides a good structural basis for realizing super-pore water pressure monitoring. During the measurement, one part of the sealed super-pore pressure measuring device penetrates into the seabed sediment, and the other part is located in the seawater. The connecting pipe of the device connects the upper seawater, and hydrostatic pressure is introduced into the inner compartment of the device to act on one side of the sensor. The pore water pressure in the sediment acts on the other side of the sensor through the permeable rock. The differential pressure value acting on both sides of the sensor is the super-hole pressure value of the sediments at the position.
However, the abyssal flow may change at any time and form a scouring and silting point on the observation point, that is, the seabed surface will become higher or lower with the effects of the abyssal flow. The sensor embedded in the superficial sediment will be completely embedded or sometimes exposed to the seabed surface with the change of the seabed surface, which will cause great inconvenience to the super-pore pressure measurement, and even cause the inability to measure the super-pore pressure value. The existing pressure observation devices still have many shortcomings in overcoming the effects of ambient dynamic changes.